Child safety seat

ABSTRACT

A child safety seat includes a seat base assembly, a sled assembly coupled to the seat base assembly, and a seat body assembly slidably coupled to the sled assembly. The sled assembly includes a modular energy absorber that is configured to reduce impact forces on an occupant of the seat body.

RELATED APPLICATIONS

This patent application claims the benefit of the filing date of U.S.patent application Ser. No. 61/537,842, entitled “Child Safety Seat”,filed Sep. 22, 2012.

FIELD OF THE INVENTION

This patent application relates to a safety seat intended forinstallation in an automotive vehicle, and particularly relates to achild safety seat having an impact absorbing mechanism that can reduceimpact forces upon a seat occupant.

BACKGROUND

Children traveling in a motor vehicle are particularly vulnerable toinjury from impact forces when the vehicle stops suddenly. Efforts havebeen made to develop child safety seats that reduce the effect of theseforces on the child. Infants are required to ride in a rear-facing childsafety seat to allow impact forces on the child's body to be absorbed bythe padding of the child seat.

An older, more robust, child may ride in a front-facing seat. In afront-facing seat, typically a multiple-point harness secures the childinto the seat. Although the child may be retained in the seat uponvehicle impact, the straps themselves can cause injury by digging intothe child. In addition certain parts of the child's body, such as thechild's head and neck, are not secured by straps and may be exposed towhiplash forces.

It is therefore desirable to reduce the impact forces that aretransferred to a child's body when the vehicle stops suddenly.

SUMMARY

As described in this patent application, there is provided a childsafety seat that includes a seat base assembly, a sled assembly that iscoupled to the seat base assembly, and a seat body assembly that isslidably coupled to the sled assembly. The sled assembly includes amodular energy absorber that is configured to reduce impact forces on anoccupant of the seat body.

The modular energy absorber may comprise an impactor piston and amonolithic energy absorbing member, and the impactor piston may beconfigured to move relative to the sled assembly, towards the energyabsorbing member, as the seat body assembly moves relative to the sledassembly. The modular energy absorber may be configured to provide astep-wise-increasing form of energy absorption as the seat body assemblymoves relative to the sled assembly. Further, the modular energyabsorber may include a skirt surrounding an end of the energy absorbingmember and configured to maintain the impactor piston in alignment withthe energy absorbing member.

In one implementation, the sled assembly comprises a pair of sled sidewalls, a sled floor, a rear end wall disposed proximate a rear of theseat, and an intermediate wall disposed proximate a front of the seat.The modular energy absorber is disposed within a sled assemblycompartment defined by the sled side walls, the rear end wall, theintermediate wall and the sled floor. The sled assembly may be coveredby a sled cover, and the impactor piston may be constrained againstrotation within the sled assembly compartment by the sled floor and alower surface of the sled cover.

The energy absorbing member may be supported by the sled floor, and theimpactor piston may be configured to translate along a plane that isparallel to the sled floor as the seat body assembly moves relative tothe sled assembly. The sled side walls may include elongate channels,and the impactor piston may be configured to translate linearly alongthe elongate channels, towards the energy absorbing member, along theplane as the seat body assembly moves relative to the sled assembly. Theimpactor piston may include an impactor channel extending therethrough,and the seat body assembly may be coupled to the sled assembly via a rodthat extends through the elongate channels and the impactor channel.

In one implementation, an end of the impactor piston includes aplurality of impactor stages that engage an end of the energy absorbingmember, each impactor stage being configured to transfer energy to theenergy absorbing member at different rates. A first of the impactorstages may comprise a primary planar impactor surface disposed proximatethe centre of the impactor piston and configured to transfer energy to afirst portion of the energy absorbing member. A second of the impactorstages may comprise a pair of secondary planar impactor surfacesdisposed on opposite sides of the primary impactor face and configuredto transfer energy to a second portion of the energy absorbing member.

The second of the impactor stages may be configured to begintransferring energy to the second portion of the energy absorbing memberafter the first of the impactor stages begins transferring energy to thefirst portion of the energy absorbing member. Further, the impactorpiston may be configured to deform the energy absorbing member at alower axial rate when the second of the impactor stages engages theenergy absorbing member than when only the first of the impactor stagesengages the energy absorbing member. The energy absorbing member mayinclude slits aligned with a lateral extent of the first of the impactorstages and configured to confine forces applied to the energy absorbingmember by the first of the impactor stages to the first portion of theenergy absorbing member.

In one implementation, the sled assembly comprises a pair of sled sidewalls, the seat base assembly comprises a pair of base side wallslocated laterally outwards from the sled side walls, each sled side wallincludes a plurality of through-holes, and each base side wall includesa plurality of arcuately-shaped base channels each aligned with arespective one of the through-holes. The sled assembly may include rodseach extending through a respective one of the through-holes andcaptured within a respective one of the base channels and configured toallow the sled assembly to move relative to the seat base assembly.Preferably, the orientation of the base channels allows the inclineangle of the seat assembly to be manually adjusted.

In one implementation, the sled side walls include elongate channelsdisposed in respective regions thereof, and the seat body assembly issecured to the sled assembly via rods extending through the elongatechannels. Each rod may be slidably retained within a respective one ofthe elongate channels, and the seat body assembly may be configured totranslate linearly relative to the sled assembly via the rods and theelongate channels.

The seat may be used both as rear-facing safety seat and a front-facingsafety seat.

BRIEF DESCRIPTION OF THE DRAWINGS

The child safety seat will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a front perspective view of the child safety seat;

FIG. 2 is a rear perspective view of the child safety seat, depictedwithout certain exterior features;

FIG. 3 is a side perspective view of the child safety seat of FIG. 2,depicting the sled assembly and the seat base assembly;

FIG. 4 is a side perspective view of the child safety seat of FIG. 3,depicting additional features of the sled assembly;

FIG. 5 is a front perspective view of the child safety seat of FIG. 4;

FIG. 6 is a side perspective view of the sled assembly and the seat baseassembly;

FIG. 7 is a front perspective exploded view of the sled assembly;

FIG. 8 (comprising FIGS. 8a, 8b, 8c ) is a collection of views of theimpactor piston and the energy absorbing member;

FIG. 9 (comprising FIGS. 9a, 9b, 9c, 9d ) is a collection of views ofthe sled assembly mounted to the base assembly;

FIG. 10 is a side plan view of the seat installed in a vehicle seat in arear-facing position; and

FIG. 11 is a side perspective view of the child safety seat showingadditional safety features thereof.

DETAILED DESCRIPTION

In FIG. 1, there is shown a fully assembled child safety seat 10intended for installation in a motor vehicle, such as a car or truck. InFIG. 2, the seat 10 is depicted without certain exterior features tothereby show some internal features of the seat 10. It should beunderstood, however, that it might not be possible to actually configurethe finished seat 10 in the manner shown, at least without damaging theseat 10.

As shown in FIG. 3, the seat 10 comprises a seat body assembly 20, asled assembly 40, and a seat base assembly 60. As will be explained, thesled assembly 40 is connected to the seat body assembly 20 and the seatbase assembly 60. When the seat 10 is mounted as a rear-facing safetyseat, the seat 10 may be secured to the vehicle by passing the vehicleseat belts through the seat body assembly 20. When the seat 10 ismounted in the vehicle as a front-facing safety seat, the seat 10 issecured to the vehicle via the seat base assembly 60. Further, in thislatter mode, the sled assembly 40 may allow the seat body assembly 20 tomove relative to the seat base assembly 60 when the seat 10 is exposedto impact forces.

In FIG. 3, the seat 10 is shown without most of the features of the seatbody assembly 20 to better show the sled assembly 40 and the baseassembly 60. The sled assembly 40 is shown in FIG. 3 covered by a sledcover 41 that is mounted to a top side of the sled assembly 40 andconceals the internal features of the sled assembly 40. The seat 10 isshown in FIG. 4 without the sled cover 41 and a remaining feature of theseat body assembly 20 to thereby provide a more unobstructed view of thesled assembly 40 and the seat base assembly 60. Again, it might not bepossible to actually configure the finished seat 10 in the manner shown,at least without damaging the seat 10.

As shown in FIG. 4, the sled assembly 40 may comprise a pair ofsubstantially parallel upright sled side walls 48, a sled floor 55 (seeFIG. 7), a rear upright end wall 49 that is disposed proximate the rearof the seat 10, and an upright intermediate wall 54 (see also FIG. 6)that is disposed proximate the front of the seat 10. Preferably, thesled floor 55, the end wall 49 and the intermediate wall 54 rigidlyinterconnect the two sled side walls 48. Further, preferably the endwall 49 and the intermediate wall 54 are disposed substantially parallelto each other. Each sled side wall 48 may preferably comprise identicalstructural features.

The base assembly 60 preferably comprises a pair of substantiallyparallel upright base side walls 64 that are located laterally outwardsfrom the sled side walls 48 and capture the sled assembly 40therebetween. While elements may be described herein with respect toonly one sled side wall 48 or base side wall 64, it should be understoodthat similar or identical elements may be present in the respectivematching opposing sled side wall 48 or base side wall 64 as well.

Each sled side wall 48 includes a rear sled cylindrical through-hole 50a and a front sled cylindrical through-hole 50 b (see FIG. 7), and eachbase side wall 64 includes a rear arcuately-shaped base channel 65 and afront arcuately-shaped base channel 66 each aligned with a respectiveone of the sled through-holes 50 a, 50 b. The sled assembly 40 includesfirst and second cylindrical base rods 61 and 62 that extendrespectively through the rear and front base channels 65, 66 (and therear and front through-holes 50 a, 50 b). To prevent the base rods 61,62 from being dislodged from the base channels 65, 66, the base rods 61,62 may be secured in place by securing hardware provided in the ends ofthe base rods 61, 62.

The base rods 61, 62 are slidingly captured within the base channels 65,66 to thereby allow the base rods 61, 62 to be guided along the lengthof the base channels 65, 66 and allow the sled assembly 40 to be movedrelative to the seat base assembly 60. As shown in FIG. 4, theorientation of the rear base channel 65 is different from theorientation of the front base channel 66 such that as the first base rod61 slides downwards within the rear base channel 65, the second base rod62 slides upwards within the rear base channel 66 and the sled assembly40 rotates about an axis that is parallel to the rods 61, 62. Therefore,movement of the sled assembly 40 via the base channels 65, 66 allows theincline angle of the seat assembly 20 to be manually adjusted.

To prevent uncontrolled movement of the sled assembly 40 relative to theseat base assembly 60, preferably the seat 10 also includes a sledlocking assembly 80 that retains the sled assembly 40 in one of aplurality of predetermined angular positions. As shown in FIGS. 5 and 6,the sled locking assembly 80 may be configured as an A-lock thatcomprises an A-shaped planar guide plate 81, a pair of locking pins 82(see FIG. 4), and a biasing spring 83. The planar guide plate 81 isdisposed between the sled side walls 48 and includes a pair ofsubstantially parallel sides (each proximate one of the sled side walls48), and a pair of guide channels 84 each extending at approximately a45 degree angle from the proximate sled side wall 48 and a positioninterior to the guide plate 81. Preferably, each base side wall 64includes a plurality of locking apertures 67, 68, 69 which are spacedapart sufficiently to provide the seat assembly 20 with three distinctincline positions. Each locking pin 82 includes a head that is capturedwithin a respective one of the guide channels 84. The locking pins 82extend from the respective guide channel 84 (through an aperture in theslide side wall 48) into one of the locking apertures 67, 68, 69.

The biasing spring 83 is coupled to the guide plate 81 and biases theguide plate 81 into a first position in which the locking pins 82 areurged laterally outwards (via the guide channels 84) into one of thelocking apertures 67, 68, 69. In order to change the position of thesled assembly 40 with respect to the base assembly 60, the guide plate81 may be pulled axially outwards, into a second position, against thebiasing force of the sled locking spring 83, to thereby withdraw thelocking pins 82 from the locking apertures 67, 68, 69 (via axialmovement of the guide channels 84). The sled assembly 40 may then bemanually rotated relative to the seat base assembly 60, and then lockedin the new position by allowing the guide plate 81 to return to thefirst position.

Where locking pins 82 are retained in the locking apertures 67, the seatassembly 20 is oriented in a substantially vertical non-reclinedposition. Where locking pins 82 are retained in the locking apertures68, the seat assembly 20 is oriented in a partially reclined position.Where locking pins 82 are retained in the locking apertures 69, the seatassembly 20 is oriented in a substantially horizontal reclined position.

As shown FIGS. 5 and 6, the seat body assembly 20 includes a pair offirst elongate slide channels 46 each disposed in a rear portion of arespective one of the sled side walls 48, and a pair of second elongateslide channels 47 each disposed in a front portion of a respective oneof the sled side walls 48. The seat 10 also includes a first slide rod42 that extends through the pair of first slide channels 46, and asecond slide rod 44 that extends through the pair of second slidechannels 47. The seat body assembly 20 is secured to the slide rods 42,44 via mounting hardware 43, 45 that is disposed at the respective endsthereof.

Preferably, each slide channel 46, 47 includes a pair of planar sidewalls that are parallel to each other, and each slide rod 42, 44 isslidably retained within the respective slide channel 46, 47. Therefore,the seat body assembly 20 is slidably coupled to the sled assembly 40via the slide rods 42, 44 and the slide channels 46, 47, and cantranslate linearly relative to the sled assembly 40.

As shown in FIG. 6, the sled assembly 40 includes a sled assemblycompartment 52, and a modular energy absorber that is disposed withinthe compartment 52. The compartment 52 comprises the region within sledassembly 40 that is defined by the sled cover 41, the sled side walls48, the rear end wall 49, the intermediate wall 54 and the sled floor55. The sled floor 55 is substantially planar within the compartment 52(see FIG. 7).

Preferably, the modular energy absorber includes an impactor piston 100and a monolithic energy absorbing member 120. The impactor piston 100includes a pair of substantially parallel planar sides, substantiallyparallel upper and lower planar faces, and an impactor bar channel 101(see FIG. 8) that extends through the impactor piston 100 between thesides thereof. The impactor piston 100 may also include a plurality ofimpactor bar teeth 102 (see FIG. 8) to add structural support to theimpactor piston 100. The first slide rod 42 extends through the pair offirst slide channels 46 and the impactor bar channel 101. Therefore, theimpactor piston 100 moves relative to the sled assembly 40, towards theenergy absorbing member 120, as the seat body assembly 20 moves relativeto the sled assembly 40.

The sides of the impactor piston 100 are disposed in close proximity tothe sled side walls 48 to keep the impactor piston 100 in alignment withthe sled side walls 48. The impactor piston 100 is supported along itslower planar face by the planar sled floor 55 of the sled assemblycompartment 52, and is constrained against rotating within the sledassembly compartment 52 by the sled floor 55 and the lower surface ofthe sled cover 41. Further, the elongate axis of the first slidechannels 46 is parallel to the sled cover 41 and the sled floor 55 (atleast within the compartment 52). Therefore, the impactor piston 100translates linearly along the first slide channels 46, towards theenergy absorbing member 120, along a plane that is parallel to the sledfloor 55, as the seat body assembly 20 moves relative to the sledassembly 40.

The energy absorbing member 120 may comprise an energy-absorbingmaterial that is formed in a monolithic layered honeycomb-likestructure. Preferably, the energy-absorbing material is aluminum, butmay be any type of deformable material.

The energy absorbing member 120 includes a leading end that is disposedproximate the impactor piston 100, a terminating end that is disposedagainst the intermediate wall 54, and upper and lower faces that extendbetween the leading and terminating ends. Preferably, the upper andlower faces are substantially planar, and are parallel to each other.Further, the intermediate wall 54 may include teeth that retain theterminating end of the energy absorbing member 120 within thecompartment 52.

The energy absorbing member 120 is supported substantially along itsentire lower planar face by the planar sled floor 55 of the sledassembly compartment 52. Therefore, the impactor piston 100 translatesalong a plane that is parallel to the sled floor 55 and the planar facesof the energy absorbing member 120 as the seat body assembly 20 movesrelative to the sled assembly 40.

To retain the impactor piston 100 proximate the rear end of the firstslide channels 46, as shown in FIG. 6, until the seat 10 is exposed toimpact forces (the “pre-impact position”), the impactor piston 100 mayinclude shear pin apertures 104 adjacent each end of the bar channel101, and the sled assembly 40 may include shear pins 103 (see FIG. 9)that extend from the sled side walls 48 into the shear pin apertures104. The shear pins 103 may be made of metal, plastic, or other materialthat allows the shear pins 103 to break when the seat 10 is exposed toimpact forces that are typically experienced in a motor vehiclecollision. In the pre-impact position, the impactor piston 100 may beseparated from the energy absorbing member 120 or may rest gentlyagainst the leading end of the energy absorbing member 120.

Preferably, the leading end of the impactor piston 100 includes aplurality of impactor stages that engage the leading end of the energyabsorbing member 120 and are configured to transfer energy to the energyabsorbing member 120 at different rates. As shown in FIG. 6, theimpactor piston 100 may comprise a first stage impactor 107 that isconfigured to axially deform and transfer energy to a first portion ofthe energy absorbing member 120, a second stage impactor 108 that isconfigured to axially deform and transfer energy to a second portion ofthe energy absorbing member 120, and a third stage impactor 109 that isconfigured to axially deform and transfer energy to a third portion ofthe energy absorbing member 120.

In the embodiment shown, the first stage impactor 107 comprises aprimary planar impactor surface 110 (see FIGS. 8 and 9) that is disposedproximate the centre of the impactor piston 100 and is configured toengage the leading end of the energy absorbing member 120. The secondstage impactor 108 comprises a pair of secondary planar impactorsurfaces 111 (see FIGS. 8 and 9) that are disposed on opposite sides ofthe primary impactor face and is configured to engage the leading end ofthe energy absorbing member 120. The third stage impactor 109 comprisesa pair of tertiary planar impactor surfaces 112 (see FIGS. 8 and 9) thatare disposed on opposite sides of the secondary impactor faces and isconfigured to engage the leading end of the energy absorbing member 120.As shown in FIG. 7, the impactor stages 107, 108, 109 may be enclosed bya skirt that surrounds at least the leading end of the energy absorbingmember 120 to further maintain the impactor piston 100 in alignment withthe energy absorbing member 120.

The first stage impactor 107 is longer than the second stage impactor108. Therefore, the second stage impactor 108 is configured to begintransferring energy to the second portion of the energy absorbing member120 (via the secondary planar impactor surfaces 111) after the firststage impactor 107 begins transferring energy to the first portion ofthe energy absorbing member 120 (via the primary impactor surface 110).The second stage impactor 108 is longer than the third stage impactor109. Therefore, the third second stage impactor 109 is configured tobegin transferring energy to the third portion of the energy absorbingmember 120 (via the tertiary impactor surfaces 112) after the secondstage impactor 108 begins transferring energy to the second portion ofthe energy absorbing member 120.

The energy absorbing member 120 may also include at least two slits 121that extend from the leading end towards the terminating end.Preferably, the slits extend part-way from the upper face towards thelower face, but do not extend into the lower face, to thereby maintainthe monolithic structure of the energy absorbing member 120. Further,the slits 121 may be aligned with the lateral extent of the first stageimpactor 107 to thereby confine the forces that are applied to theenergy absorbing member 120 by the first stage impactor 107 to the firstportion of the energy absorbing member 120.

As shown, the surface area of the impactor surface 110 of the firststage impactor 107 is less than the combined surface area of theimpactor surfaces 110, 111 of the first and second stage impactors 107,108. Therefore, the impactor piston 100 is configured to deform theenergy absorbing member 120 at a lower axial rate when the second stageimpactor 108 engages the energy absorbing member 120 than when only thefirst stage impactor 107 engages the energy absorbing member 120.Similarly, the combined surface area of the impactor surfaces 110, 111of the first and second stage impactors 107, 108 is less than thecombined surface area of the impactor surfaces 110, 111, 112 of thefirst, second and third stage impactors 107, 108, 109. Therefore, theimpactor piston 100 is configured to deform the energy absorbing member120 at a lower axial rate when the third stage impactor 109 engages theenergy absorbing member 120 than when only the second stage impactor 108engages the energy absorbing member 120. Accordingly, the modular energyabsorber is configured to provide a step-wise-increasing form of energyabsorption as the seat body assembly 20 moves away from the pre-impactposition.

As will be apparent, the impactor piston 100 need not comprise threeimpactor stages, and the impactor stages need not each comprise planarimpactor surfaces. Rather, the impactor piston 100 may have any numberof impactor stages, and the impactor stages may have other shapes andrelative sizes, depending on the dampening profile desired. However,preferably the layout of the staged impactors is symmetrical about thecentre of the impactor piston 100 to allow for even distribution offorces and to encourage linear movement of the impactor piston 100 alongthe first slide channels 46.

When a vehicle having the seat 10 stops suddenly, such as in a vehiclecollision, and the seat 10 is installed into the vehicle in aforward-facing direction, the shear pins 103 will break apart due to thesummation of impact forces applied to the shear pins 103 from themomentum of the child and the sudden stopping of the sled assembly 40and the base assembly 60 (the latter being rigidly secured to thevehicle). When the shear pins 103 break, the seat body assembly 20continues to travel forwards while the base assembly 60 and the sledassembly 40 stop suddenly. The movement of the seat body assembly 20relative to the sled assembly 40 causes the impactor piston 100 to slidewithin the rear slide channels 46 and the second slide rod 44 to slideunopposed within the front side channels 47.

As the impactor piston 100 slides forward, it engages the leading end ofthe energy absorbing member 120, thereby causing the impact forces onthe child to be transferred through the impactor piston 100 to theenergy absorbing member 120, and the energy absorbing member 120 tostep-wise deform as it dissipates the impact forces. Depending on theweight of the child and the seat body assembly 20, the impactor piston100 may cause varying amounts of the energy-absorbing material tocollapse, thereby bringing the child and child seat body assembly 20 toa more gradual stop than normal.

Since the impactor piston 100 translates linearly along the first slidechannels 46, instead of rotating about the slide channels 46, as theimpactor piston 100 moves towards the energy absorbing member 120, theimpactor piston 100 is able to efficiently distribute the impact forceto the entire leading end of the energy absorbing member 120.Furthermore, since the modular energy absorber is enclosed by the sledcover 41, the sled side walls 48, the sled end wall 49, the intermediatewall 54 and the sled floor 55 of the sled assembly 40, lateral, upwards,or downwards movement of the impactor piston 100 and the energyabsorbing member 120 is limited. Therefore, impact forces on the childare efficiently transferred to the energy absorbing member 120.

Preferably, the sled assembly 40 is formed from a lightweight material,such as magnesium alloy or plastic, and has a uni-body construction toimpart strength and lightness to the sled assembly 40. Similarly, theseat base assembly 60 preferably also has a uni-body construction and isformed from a magnesium alloy. By eliminating weld points in theconstruction of assemblies 40 and 60, each assembly 40 and 60 isstrengthened allowing impact forces to flow through the seat 10 withoutcausing damage to elements of the seat 10 other than the shear pins 103and the energy absorbing member 120. Although it is preferable that theimpactor piston 100 move towards the energy absorbing member 120, in onevariation the energy absorbing member 120 may move towards the impactorpiston 100, to thereby collapse the energy absorbing material.

The safety seat 10 may be installed in a vehicle in either a rear-facingdirection via seat belts threaded through the seat 10 (see FIG. 10), ora forward-facing direction via bracing arms 71 (see FIG. 11) that extendfrom the base assembly 60 towards the vehicle seat. When the seat 10 isinstalled in a rear-facing direction, it is desirable to be able todisable the translation movement of the impactor piston 100 to preventre-coil movement of the seat 10 after the impact. Also, according toexisting safety standards, when a child seat is installed in arear-facing direction it must be reclined more than when installed in aforward-facing direction. Therefore, as shown in FIG. 11, preferably theseat 10 also includes rear dampening locks 130 each pivotally coupled toa respective exterior side of the sled side wall 48 and are configuredto engage lock guide edge 70 of the base assembly 60. As the sledassembly 40 is moved to a reclined position, as previously described,the dampening locks 130 are biased to ride along the guide edge 70 by arear dampening lock spring 131 (shown in FIG. 4). Upon the sled assembly40 being locked into a fully reclined position, the dampening locks 130will be urged upwards by the guide edge 70 into a position whereby theycapture a respective end of the second slide rod 44, thereby preventingthe second slide rod 44 from moving during impact. Since the secondslide rod 44 is secured to seat body assembly 20, as is first slide rod42, the seat body assembly 20 will thereby be prevented from movingrelative to the sled assembly 40 during vehicular impact.

When the seat is installed in a forward facing direction, the seat 10will be in a non-reclined position in which the dampening locks 130 willnot engage the second slide rod 44. However, in vehicles that do notfeature child seat safety mounting parts, such as ISOFIX components, theseat 10 may be secured in the vehicle by strapping the vehicle seatbelts through portions of the seat 10. In such an installation, it alsomay be desirable to disable the impactor piston 100. Therefore, as shownin FIG. 11, preferably the seat 10 also includes front dampening locks140 through which the vehicle seat belt may be threaded.

The front dampening locks 140 are normally biased upwards away from thefirst slide rod 42 by a front dampening lock spring 142 (shown in FIG.4). However, if a vehicle seat belt is threaded through channel 141 ofthe front dampening locks 140 and the seat belt is tightened, thedampening locks 140 will be urged downwards to capture a respective endof the first slide rod 42 and thereby prevent the seat body assembly 20from moving relative to the sled assembly 40 during a vehicular impact.

The invention claimed is:
 1. A child safety seat comprising: a seat baseassembly; a sled assembly coupled to the seat base assembly and a seatbody assembly slidably coupled to the sled assembly, wherein the sledassembly is configured to allow linear movement of the seat bodyassembly relative to the sled assembly when the seat is exposed toimpact forces, and includes a modular energy absorber configured toreduce the impact forces on an occupant of the seat body assembly, andwherein the seat base assembly is configured to selectively allow thesled assembly to move relative to the seat base assembly independentlyof the movement of the seat body assembly relative to the sled assembly.2. The child safety seat according to claim 1, wherein the modularenergy absorber comprises an impactor piston and a monolithic energyabsorbing member, and the impactor piston is configured to move relativeto the energy absorbing member as the seat body assembly moves relativeto the sled assembly.
 3. The child safety seat according to claim 2,wherein the modular energy absorber is configured to provide astep-wise-increasing form of energy absorption as the seat body assemblymoves relative to the sled assembly.
 4. The child safety seat accordingto claim 2, wherein the modular energy absorber includes a skirtsurrounding an end of the energy absorbing member and configured tomaintain the impactor piston in alignment with the energy absorbingmember.
 5. The child safety seat according to claim 2, wherein the sledassembly comprises a pair of sled side walls, a sled floor, a rear endwall disposed proximate a rear of the seat, and an intermediate walldisposed proximate a front of the seat, and the modular energy absorberis disposed within a sled assembly compartment defined by the sled sidewalls, the rear end wall, the intermediate wall and the sled floor. 6.The child safety seat according to claim 5, wherein the sled assembly iscovered by a sled cover, and the impactor piston is constrained againstrotation within the sled assembly compartment by the sled floor and alower surface of the sled cover.
 7. The child safety seat according toclaim 5, wherein the impactor piston includes upper and lower faces andthe impactor piston is supported along the lower face by the sled floor.8. The child safety seat according to claim 2, wherein the sled assemblycomprises a sled floor, the energy absorbing member is supported by thesled floor, and the impactor piston is configured to translate along aplane that is parallel to the sled floor as the seat body assembly movesrelative to the sled assembly.
 9. The child safety seat according toclaim 8, wherein the sled assembly comprises a pair of sled side wallsthat include elongate slide channels, and the impactor piston isconfigured to translate linearly along the elongate slide channels,towards the energy absorbing member, along the plane as the seat bodyassembly moves relative to the sled assembly.
 10. The child safety seataccording to claim 9, wherein the impactor piston includes an impactorchannel extending therethrough, and the seat body assembly is coupled tothe sled assembly via a slide rod that extends through one of theelongate slide channels and the impactor channel.
 11. The child safetyseat according to claim 10, wherein the impactor piston includes shearpin apertures disposed adjacent the impactor channel, and the sledassembly includes shear pins extending from the sled side walls into theshear pin apertures, the shear pins being configured to break when theseat is exposed to an impact force.
 12. The child safety seat accordingto claim 2, wherein an end of the impactor piston includes a pluralityof impactor stages that engage an end of the energy absorbing member,each impactor stage being configured to transfer energy to the energyabsorbing member at different rates.
 13. The child safety seat accordingto claim 12, wherein a first of the impactor stages comprises a primaryplanar impactor surface disposed proximate the centre of the impactorpiston and configured to transfer energy to a first portion of theenergy absorbing member, and a second of the impactor stages comprises apair of secondary planar impactor surfaces disposed on opposite sides ofthe primary impactor face and configured to transfer energy to a secondportion of the energy absorbing member.
 14. The child safety seataccording to claim 13, wherein the second of the impactor stages isconfigured to begin transferring energy to the second portion of theenergy absorbing member after the first of the impactor stages beginstransferring energy to the first portion of the energy absorbing member.15. The child safety seat according to claim 14, wherein the impactorpiston is configured to deform the energy absorbing member at a loweraxial rate when the second of the impactor stages engages the energyabsorbing member than when only the first of the impactor stages engagesthe energy absorbing member.
 16. The child safety seat according toclaim 13, wherein the energy absorbing member includes slits alignedwith a lateral extent of the first of the impactor stages and configuredto confine forces applied to the energy absorbing member by the first ofthe impactor stages to the first portion of the energy absorbing member.17. The child safety seat according to claim 2, wherein the energyabsorbing member comprises an energy-absorbing material having amonolithic layered honeycomb-like structure.
 18. The child safety seataccording to claim 17, wherein the energy-absorbing material isaluminum.
 19. The child safety seat according to claim 1, wherein thesled assembly comprises a pair of sled side walls, the seat baseassembly comprises a pair of base side walls located laterally outwardsfrom the sled side walls, each sled side wall includes a plurality ofthrough-holes, and each base side wall includes a plurality ofarcuately-shaped base channels each aligned with a respective one of thethrough-holes.
 20. The child safety seat according to claim 19, whereinthe sled assembly includes base rods each extending through a respectiveone of the through-holes and captured within a respective one of thebase channels and configured to allow the sled assembly to move relativeto the seat base assembly.
 21. The child safety seat according to claim20, wherein the orientation of the base channels enables an inclineangle of the seat body assembly to be manually adjusted.
 22. The childsafety seat according to claim 19, wherein the seat further comprises alocking assembly configured to selectively allow the sled assembly to berotated relative to the seat base assembly and to retain the sledassembly in one of a plurality of predetermined angular positionsrelative to the seat base assembly.
 23. The child safety seat accordingto claim 22, wherein each said base side wall includes a plurality ofapertures, the locking assembly comprises a guide plate and at least onelocking pin, the guide plate includes a guide channel, a head of thelocking pin is captured within the guide channel, and the guide channelis configured to maintain the locking pin in one of the lockingapertures in accordance with a position of the guide plate.
 24. Thechild safety seat according to claim 1, wherein the sled assemblycomprises a pair of sled side walls, the sled side walls includeelongate slide channels disposed in respective regions thereof, and theseat body assembly is secured to the sled assembly via slide rodsextending through the elongate slide channels.
 25. The child safety seataccording to claim 24, wherein each slide rod is slidably retainedwithin a respective one of the elongate slide channels, and the seatbody assembly is configured to translate linearly relative to the sledassembly via the slide rods and the elongate slide channels.